Peripheral grinding wheels with tool rests are commonly used. In practice, a part is placed on the grinder's tool rest and advanced into the rotating wheel along the tool rest, to grind material from the part to obtain a new surface, matching the wheel contour. When appropriate, it is desirable to know or control the angle ground into a part before it is ground to prevent guessing and wasted effort. This can be accomplished by finding a measurable geometric relation for the part and the grinding wheel set-up. When the part is on the grinding wheel and viewed from the center line of the grinding wheel, an end view, the ground contour in the vertical plane is commonly identified by an acute angle. See FIG. 4. The angle on the part is formed from an imaginary line passing through the end points of the contour intersecting with a line corresponding to the body of the part, usually registering on the tool rest. The intersection of these two lines, the vertex of the angle, can be considered the effective pivot point, controlling the angle ground on the part. This effective pivot point is the common feature between the newly ground and existing register surface of the part guided by the tool rest. Similarly for the grinding wheel, this same effective pivot point is a way to locate the tool rest's angular position relative to the wheel contour. The effective pivot point coincides with the intersection of the wheel periphery and the tool rest plane. The wheel periphery is identical to the ground contour and the register surface of the part follows the tool rest plane. With the effective pivot point identified it then is possible to describe the geometric relationship between the grinding wheel contour and the tool rest plane. In this way it can be recognized that the effective pivot point is a critical feature in determining both the grinding wheel set-up and the angle ground into a part.
Tool rests, however, are typically pivoted about a convenient point on the machine frame away from the wheel periphery and not at the effective pivot point. A tool rest pivot point removed from the wheel periphery merely serves as a convenient way to mark the change in the tool rest angle, not define it. The effective pivot point and not the machine frame pivot must be considered in order to define the geometric relationship between the wheel periphery and its tool rest in a vertical plane. The angle formed by the contour ground into a part should be determined by wheel contour (size) and the location of the tool rest plane relative to the intersection between these two surfaces. It is the combination of these two surfaces relative to the effective pivot point that determines the angle on the part.
Up to now, controlling the ground angle has been limited to positioning apparatus integral to the grinding wheel machine or required trial and error with post grinding measurement using a protractor or gaged comparaters, time consuming practices.
This invention is a separate angle measuring device that provides accurate angle definition of the machine set-up in the vertical plane. It is an accessory to existing equipment. It can be used for any conventional angle between 0 degrees and 90 degrees and can be used on more than one grinder.